Cardiopulmonary arrest or impending cardiopulmonary arrest occurs commonly in hospital emergency departments and in prehospital settngs (ambulances, etc.). In such situations, it is routine for a physician, paramedic, or other qualified person to insert a breathing tube through the mouth or nose into the patient's trachea. Such a tube is called an "endotrachael tube." After an endotracheal tube is placed in the correct anatomical position, it may be attached to an oxygen source and mechanical ventilation performed. Typically, in such patients, mechanical ventilation with oxygen is in itself not sufficient to resuscitate successfully. Therefore, in addition to artificial ventilation, certain life-saving drugs may be necessary to help "restart" the heart. Such drugs are typically administered into the patient's bloodstream via an intravenous (IV) canula. Such canulas are placed in a systemic vein, such as an arm vein or large chest vein (in contrast to a pulmonary vessel). However, in recent years, it has been found that certain life-saving drugs, such as epinephrine, atropine, and lidocaine, also may be administered through the pulmonary (lung) vasculature. Patients receiving drugs via the pulmonary route have been documented to respond in a similar fashion as do those patients receiving drugs via systemic (arm or chest) administration. As a result of these discoveries, it is now the accepted standard practice to use the endotrachel route for life-saving drug administration if for some reason systemic venous access is not available. Since canulating a systemic vein is time-consuming or even impossible in many patients experiencing cardiopulmonary arrest, and since time is of the essence in administering life-saving drugs to these patients, the endotracheal route is often used during cardiopulmonary resuscitation. Currently, the accepted technique for administering endotracheal drugs involves the injection of the selected drug into the proximal end of the tube and then "blowing" the drug down the tube into the lungs. Deep in the lungs, the drug easily diffuses from the small air spaces (alveoli) through the air-blood membrane into the bloodstream.
With the current "state of the art" endotracheal tube, there are problems with administering endotracheal pharmaceuticals. Such problems are:
(1) interruption of artificial ventilation. In order to inject liquid medicine into the proximal end of an endotracheal tube, the mechanical breathing device must be removed, thus interrupting ventilation. There is no port in the endotracheal tube which is exclusively dedicated to drug administration.
(2) questionable delivery of drugs to the target tissue. Oftentimes during cardiopulmonary resuscitation, pulmonary secretions will collect in the endotracheal tube. When drugs are injected into the endotracheal tube, varying amounts of such drugs may be absorbed into thick secretions and be mechanically blocked from entering the lungs.
(3) questionable metering of endotracheal drugs. Even if the endotracheal tube is completely free of secretions, there is still the problem of metering the drug. Since the endotracheal tube has an extremely large diameter (usually seven to eight millimeters in adults, with decreasing dimensions corresponding to decreases in patient size) in relationship to the volume of fluid to be injected (usually five to ten millileters of fluid), a significant percentage of drug may adhere to the wall of the tube due to surface tension phenomena. Accordingly, the measure of drug injected into the proximal end of the endotracheal tube may not be the same measure which exits through the distal end of the tube and subsequently enters the pulmonary circulation.
Also the diameter-to-volume ratio makes a forcible, quick introduction of drug to the lung impossible. Rather, a drug is introduced into the endotracheal tube and then "blown" into the lungs when mechanical ventilation is reinstated.
Accordingly, it is the object of this invention to overcome the aforesaid problems and to provide an improved apparatus for and method of introduction of medication under emergency circumstances or where otherwise intravenous injection of medication is not feasible.